Bundling ties have been used extensively for securing objects, such as utility lines. Bundling systems often comprise a tie head and strapping material that is wrapped around the items to secure and then inserted through passageways in the tie head. Two approaches include a one-piece unit that combines the tie head with a fixed length of strapping material. A second approach includes a two-piece system with a tie head and strapping material that can be cut to the desired length. The present invention deals with the two-piece bundling system.
U.S. Pat. No. 5,544,391 to Hoffman utilizes a one-piece V-shaped pawl pivotally mounted within the housing for engagement with a strap. A similar solution can be found in U.S. Pat. No. 6,128,809 to Khokhar, which teaches a one-piece locking device with two barbs for independent deflectable locking engagement with strapping material. However, these solutions have certain limitations associated with the design including distortion of the locking device and ultimate failure of the head under high load conditions.
A second focus has been on the configuration and implementation of the locking device within the tie head housing. The shape of the locking device as well as the engagement edge has been addressed in order to provide a more secure engagement with the strapping. For example, U.S. Pat. No. 6,532,631 to Rohaly teaches a flat T-shaped locking device with a beveled knife-edge. The T design, however, is susceptible to failure as the narrow portion of the device can distort and fail under heavier loads. In addition, the beveled knife-edge can cut through a significant portion of the strap material under heavier loads or slide along the strap causing premature failure of the head.
A further attempt to improve engagement with a strap without destroying the integrity of the strap under load is covered in U.S. Pat. No. 5,193,251 to Fortsch. Fortsch teaches a bundling tie employing a pair of movably supported locking barbs, with each barb having an engagement portion comprising a knife-like element for biting insertion into the strap and a blunt stop wall adjacent to the knife-like element for limiting the depth of insertion of the knife-like element into the strap.
While each of the above designs provides certain benefits, there has been a continuing effort directed to improving the performance of bundling ties including the ease of use, reliability and longevity of the tie as well as the ability to securely bundle multiple items in high stress environments with little, if any, slippage of the strap. The present invention overcomes the above limitations and provides a simple, lightweight and cost effective solution that combines an elegant design with superior performance.